Answer this question truthfully
### Question: What causes Pneumothorax?
### Response: A collapsed lung may result from chest trauma, such as gunshot or knife wounds, rib fracture, or after certain medical procedures.
In some cases, a collapsed lung occurs without any cause. This is called a spontaneous pneumothorax. A small area in the lung that is filled with air, called a bleb, ruptures, and the air leaks into the space around the lung.
Certain activities may lead to a collapsed lung. These include scuba diving, smoking marijuana or cigarettes, high altitude hiking, and flying.